Control mechanism for vertical hydraulic broaching machines



March 3, 1942. K. c. MoNloE 2,275,196 CONTROL MECHANsM FOR vERTCALHYDRAULIC BROACHING MACHINES Filed July 12, 1938 4 Sheets-Sheet 1 March3, 1942. K, c, MQNROE CONTROL MECHANISM FOR VERTICAL HYDRAULIC BROACHINGMACHINES 4 Sheets-Sheet 2 Filed July l2, 1938 March 3, 1942. K, c.MoNRoE CONTROL MECHANISM FOR VERTICAL'HYDRAULIC BROACHING MACHINES FiledJuly l2, 1938 4 Sheets-Sheet 5 TNNN |||.l||| IIIIZIIIIII llllllll March3, 1942.

K. c. MONROE` 4 sheets-sheet 4 Filed July 12,21958 Nlhllllillll NN MNIMLf. a

l www? -----Iiwmml i i Inde Patented Mar. 3, 1942 CONTROL MECHANISM FORVERTICAL HYDRAULIC BROACHING MACHINES Kenneth C. Monroe, Hudson, Mass.,assignor to The Lapointe Machine Tool Company, Hudson, Mass., acorporation of Maine Application July 12, 1938, Serial No. 218,870l

(Cl. Sii-33) 17 Claims.

This invention relates to a vertical hydraulic breaching machine andmore particularly to broaching machines of the pull-down ty-pe in whichpower-operated devices are provided for restoring the broach to raisedposition. a machine is shown for instance in the prior patent to DonaldH. West, No. 2,135,157, dated November 1, 1938.

It is the general object of this present application to provideelectrical and hydraulic control devices so interlocked that successivesteps in the operation of the machine must be performed in predeterminedsequence.

In particular, I provide means insuring that the finished work piecemust be removed before the broach is raised, and insuring that thepuller head must be fully raised before the breach is lowered byreversal of the broach lifter.

I also provide devices which insure insertion and subsequent removal ofthe broach-holding key at deiinite points in the operation of themachine, and which prevent further operation of the machine until suchinsertion or removal has taken place.

My invention further relates to arrangements and combinations of partswhich will be hereinafter described and more particularly pointed out inthe appended claims.

A preferred `form of the invention is shown in the drawings, in which-Fig. 1 is a diagrammatic representation of a vertical hydraulicbreaching machine of the pulldown type, together with its hydraulicactuating mechanism and with certain hydraulic and electric interlockingdevices;

Figs. 2 to 6 inclusive are similar diagrammatic views showing successivepositions of different parts of the machine and control devices during abroaching operation; and

Fig. '7 is a sectional side elevation of a breaching machine of the typeto which my invention is particularly applicable.

Referring to Figs. 1 and 7, I have shown parts of a vertical pull-downbreaching machine comprising a puller head I mounted on a slide or ramII and connected by a piston rod I2 to a piston I4 slidable in a maincylinder I5. A pump P is connected by a pipe I6 to the upper end of thecylinder I and is connected by a pipe I1 to the lower end of saidcylinder.

A back pressure valve I8 is inserted in the pipe I1, and a branchconnection I9 is provided, through which extra oil may be supplied tothe pump during the working or downward stroke. During the up stroke,the pipe I9 is closed by a check valve 20.

The pump P is preferably a variable-discharge,

`reversible pump and may be of the type shown in the prior patent toWest, No. 1,722,832. -The Such pump P is controlled by a rack bar2I andpinion 22, as in said prior patent, and the rack bar2l is shown asconnected by a link 23 to a rock arm 24 mounted on a iixed pivot 25.

A knock-off rod 26 has a pin and slot connection with the rock arm 24and is provided with adjustable collars 21 and 28 positioned forengagement by an arm 3U mounted on a rod 3| which in turn is supportedon an upper part oi the ram or slide II. When either collar 21 or 28 isengaged by the arm 30, the rock arm 24 is returned to mid-position andthe pump P is adjusted for no-discharge.

A hand lever 33 is pivoted at 34 and has an arm 35 connected by a link36 to the rock arm 24. A second arm 31 is connected by a link 38 andpiston rod 39 to a piston 40 in a relay cylinder 4 I, said relay beingprovided for power operation of the pump-adjusting mechanism.

The cylinder 4I is connected by pipes 42 and 43 to spaced ports in thevalve casing 44 ofI a solenoid-operated valve V.

A continuous-discharge auxiliary pump P is connected through a reliefvalve 45 and pipe 45 to a supply port in the valve casing 44, andconnections 41 and 48 are provided from said casing to storage atatmospheric pressure.

A piston comprising two spaced piston elements is slidable in the casing44 and is provided with a valve rod 5I connected to a bell crank 52pivoted at 53 and having a portion 54 extending between electro-magneticor solenoid coils 55 and 56 and adapted to be attracted thereby. Opposedsprings 5Ia on the pisto-n rod 5I normally center the piston 50 inneutral position, unless displaced therefrom by one or the other of thecoils 55 or 56.

Connection is made from a line wire L to each of the coils 5 and 56, andconnection is made from the coil 55 through a photoelectrio relay 5l toa normally-open switch 58. The coil 55 is similarly connected to a wire59 through a normally-open switch 60. The other terminals of theswitches 58 and 60 are connected by a return wire 6I to a second linewire L.

If' the switch 6U is closed, the coil 56 will be energized, shifting thepiston 56 in the valve V to the left and applying pressure through thepipe 43 to the lower end of the relay cylinder 4I. This raises thepiston 40 and also raises the rack bar 2| and knock-off rod 26. Suchmovement of the rack bar will cause uid under pressure to be suppliedthrough the pipe I6 to the I the pipe I1 and thus return the piston I4and ram to upper position.

The devices for hydraulically operating the rack bar 2|, except for theelectrical control, are similar to the corresponding devices shown anddescribed in my prior application, Serial No. 169,581 to which referenceis made for a more detailed description.

The pipe I6 is also connected through a normally-closed valve 63 to avent pipe 64. The valve 63 has a pressure connection 65 to the pipe I1,and the construction is such that pressure in the connection 65 willopen the valve 63 and vent the pipe I6 to storage. This permits theescape of surplus oil from the upper end f the cylinder during an upstroke, corresponding to the increasing amount of oil displaced by thepiston rod as the piston I4 moves upward.

During the broaching stroke, the lower end of the broach B is secured inthe puller head I0 by a key 10 and I will now describe certain deviceswhich I have provided for inserting and removing the key and forinterlocking the movements of the key with the operation of thebroaching machine.

The key 10 is connected by a link 1| to an upwardly extending arm of afour-armed lever 12, pivoted at 13 on a depending support 14 carried bythe ram II. A second arm 15 of the lever 12 has a toggle connection to aspring plunger 16 mounted on a pivot 11. This spring toggle connectioncauses the lever 12 to be held in one or the other of its extremepositions, as determined by stop pins 18, the construction being similarto that shown and described in the prior application of John W. Forbes,Serial No. 189,744, led February l0, 1938.

A third arm 80 on the lever 12 engages a fixed stop 8| as the ram IIapproaches its lower limit of travel and the lever 12 is reversedthereby, thus withdrawing the key 10 from holding position.

VThe fourth arm 82 of the lever 12 is provided with a ball-shaped headpositionedv between spaced lugs 83 and 84 on a hand lever 85, pivoted at86 on the support 14 and normally held in mid-position by a spring 81.The upper portion of the handle 85 extends between the normallyopenswitches 58 and 60 associated with the coils 55 and 56 andis adapted toclose one or the other of these switches when displaced to the right orto the left. l

When moved to the left, the lever 85 will reverse the four-armed lever12, moving the lever to the position shown in Fig. 3 and inserting thekey 10 in broach-holding position. Also, when thus moved to the left,the lever 85 engages and closes the switch 60, thus energizing the coil56 and causing the pump P to be shifted to effect a broaching ordown-stroke of the ram, all as previously described.

The key-shifting lever 12 is automatically returned to the positionshown in Fig. 1 by engagement of the arm 80 with the stop 8| at thelower end of the breaching stroke. Such return movement does not,however, displace the lever I85 from its normal mid position, by reasonof the spaced relation of the lugs 83 and 84. The lever 85 may bethereafter moved manually to the right to close the switch 58 and setthe pump P for a return stroke of the ram II. Such movement of the lever85 to the right will manually reverse the lever 12 and withdraw the key10, if for any reason these parts have not been moved automatically by`engagement of the arm 80 and stop 8 I.

The broach lifter mechanism is of the general type disclosed in saidprior application Serial No. 125,871 and comprises a lifter head 90mounted on a piston rod 9| and actuated by a piston 92 in a liftercylinder 93.

A second auxiliary pump P2 is connected through a pilot-operated reliefvalve S4 and through an adjustable needle valve 95 to a supply port inthe casing 96 of a solenoid-operated valve V', which casing is providedwith three additional ports, one of which is connected through a pipe g91 to the upper end of the cylinder 93. Another port is connectedthrough a pipe 98, back pressure valve 99 and check valve |00 to thelower end of the cylinder 93. A Icy-pass |0|`is provided around thecheck valve 0|), which bypass contains an adjustable needle valve |02. Afourth port in the casing 06 is connected to an exhaust pipe |03rthrough which oil may be returned to storage. f

One terminal of a solenoid coil |05 at the left-hand end of the valve Vis connected through a wire IIO, normally-open hand switch III, wire||2, limit switch ||3 and wires II 4 and 6| to the line wire L. solenoidcoil |05 is connected through a return wire |I5 to the line wire L.

One terminal of the solenoid coil |20 .at the right-hand end of thevalve V is also connected through the return wire |I5 to the line wireL, while the other terminal is connected through a wire I2| to anormally-open Switch |22, which in turn is connected through a wire |23to the line wire L'.

The lifter head 98 is provided with a broachholding device |25 fromwhich a broach is automatically released by cam action at apredetermined point in its downward travel, 'all as fully explained inthe cited West application.

A latch |26 is pivotally mounted on the lifter head and passes freely bythe switch |22 when moved downward but closes the switch on engagementthereof when moving upward. i

Upper and lower control valves |30 and I3| are provided in connectionwith the lifter mechanism, which valves are normally closed butareprovided vvith actuating members |32 and |33'r respectively, whichmembers are positioned for alternate engagement'by a cam plate |34 onthe lifter head 90, according as the lifter head is in raised or loweredposition;

A pipe |36 connects the supply pipe 01 for the upper end of the cylinder93 to a port inthe lower side of the upper control valve |30, and a pipe|31 connects the supply pipe 98 for the lower end of the cylinder 93 toa similar port in the lower side of the valve I3'I.

Upper ports in thevalves .|30 and I3I `are connected to a control pipeI40,'which pipe is in turn connected to the pilot-operated relief Valve94. The valve 94 is of a commercial construction such that lack ofpressure in the pipe |40 will connect the pump P2 direct tothe exhaustpipe |4I, so that the oil discharged from the pump is returned direct tostorage. When there is pressure in the pipe |40, however, kthe reliefvalve 94 is closed and the pump P2 is connected to the supply pipe |42of the valve V'. A small bypass opening in the valve 94 will build uppressure in the pipe |40 and close the relief valve 94 unless one of thevalves |30 and |'3Iis open to atmosphere. l

The general operation of my improved broaching machine i's as follows:fThe machine is stopped with the broach B suspended from theraised Theother terminal of the lifter head 90 as Aindicated at A in Fig. 7, andwith the ram also in raised position.

After the -work has been placed on the fixed work` support |5|la (Fig.7) the lifter head moves Vthe breach downward to position C, thusinserting the lower end ofthe breach B in the puller head of thev ram@The'work in this position intercepts the light ray which controls thephotoelectric relay l and thus opens the operating circuit of thesolenoid coil 55;

The ram is then started downward and the breachy is pulled through thewerk by the ram, while at the same time the lifter head exerts downwardpressure on the upper end of the breach. As the breaching operationnears completion and the breach is moved down to position D, the lifterhead |25 is unlatched to free the breach and the lifter head comes torest. The ram I continues its downward motion and pulls the breachentirely through the work to position whereupon the ram and breach cometo rest and the `key 'l0 is automatically withdrawn.

The work is then removed, and the ram is started upward, thereby againinserting the upper end of the broach in the lifter head |25 andmechanically moving the lifter head upward far enough to release thebreach holder |25 for re-` engagement with the breach.

The lifter head then moves rapidly upward, drawing the breach out of thebreach holder |0 and'returning it to the position A. The machine thencomes to rest, with the breach lifter,`broach and ram all in raisedposition. This general operation is substantially as described in theprior West application Serial No. 125,871.

. I will new describe in detail the operation of l the hydraulic andelectric control devices by which successive steps in the operationabove outlined are caused to take place in predetermined order and nototherwise.

Assuming that the parts are in the position indicated in Fig. l, withthe breach in the position A of Fig. 7, it will be noted that the limitswitch ||3 is closed by engagement with the ram in itsraised position.The pump control valve V is in its normal mid-position, the main pump Pis in neutral, and the lifter control valve V is in its right-handposition, with the pump P2 connected to the lower end of the cylinder 93but discharging to storage through the exhaust connection bilby reasonof the fact that the control pipe M0 is vented through the open controlvalve |33.

The operator now closes the switch which shifts the valve V to theleft-hand position shown in Fig. 2. The pump P2 is thereby connectedthrough the pipe 91 to the upper end of the lifter cylinder 93 and isalso connected through the pipe |39 and open valve |30 to the controlpipe |40, so that pressure is immediately built up in the pipe to closethe pilot-operated relief valve 94.

The lower end of the cylinder 93 is connected to the exhaust through theneedle valve |02 and back 'pressure valve 99, and the lifter head 90moves the lower end of the breach B downward through the work andinserts said lower end in the puller head |9 on the ram Il. The pump P2continues to exertpressure above the piston 92 in the cylinder 93, butas no further movement of the piston can take place, the pump P2discharges to l atmospherev through the valve 94,

which at this time acts merely as an ordinary relief valve'. 1

The operator then shifts the hand lever 85 to the left as shown in Fig.3, thereby inserting the key 'l0 in the lower end of the breach B andclosing the switch which operates through the valve V and relay cylinder4| to set the pump P for a down stroke, all as previously described.

As soon as the handle is released, the handle returns to mid position,allowing the switch 60 to open and the valve V to return to midposition. This vents both ends of the cylinder 4| and leaves the pump Pfree for mechanical shifting to no-discharge position at the end of thebreaching stroke.

If the operator inadvertently operates the lever 05 before closing theswitch the cam will merely be moved downward idly without the breach andthe lifter head will remain in raised position, as the circuit throughthe switch l|| cannot be completed after the ram has moved away from thelimit switch H3, which will then open.

The ram and breach lifter continue to move downward together, both underpressure, until the breach holder |25 engages a fixed cam |50 (Fig. 4)which releases the breach. At the same time the cam |34 on the breachlifter 90 engages and opens the control valve |3|, thus venting thecontrol pipe |40 which in turn causes the valve 94 to connect the pumpP2 to exhaust. The back pressure valve 99 prevents idle downwardmovement of the lifter head.

As the ram and breach B reach their lower limit of travel, the arm 80(Fig. 5) of the lever 'l2 engages the stop 8| and thelever l2 isreversed thereby, thus withdrawing the key 70 but leaving the hand lever95 in mid position. At the same time, the knock-off arm 39 engages thelowei` collar 28 on the rod 25 and moves the pump P to neutral orno-discharge position.

The operator then removes the work, after which he moves the hand lever85 to the right,

as also shown in Fig. 5, te close the switch 58. If he closes the switchbefore removing the work,

however, no action will follow, as the photo? electric relay 5l willremain open as long as its controlling light ray is intercepted by thework. Assuming that the work has been removed, closing of the switch 58will energize the coil 55, moving the piston 50 in the valve V to aposition shown in Fig. 5 and moving the pump P to its reverse positionin which it delivers oil under pressure to the pipe I'l and raises theram As the breach B is thus moved upward, it is re-inserted in thebreach holder |25 (Fig. 6) of the lifter head and pushes the lifter headupward far enough to permit the breach holder to clear the cam |59 andthereupon grip the breach. Such upward mechanical movement of the breachlifter can take place freely, as the oil ejected from the upper end ofthe cylinder will escape through the relief valve 94, which is open byreason of the fact that the control pipe |40 is still vented through thecontrol valve I3! as shown in Fig. 4.

As soon as the lifter head 90 has moved a short distance upward,however, the cam |34 releases the valve |3| and the latch |25 closes theswitch |22. This completes the circuit through the solenoid coil |20 inthe valve V', shifting the valve to the position shown in Fig. 6 andconnecting the ptunp P2 to the lower end of the lifter cylinder 93. Bothcontrol valves |30 and |31 being new closed, pressure will be built upin the pipe |48 through the by-pass in the valve 94, the valve 94 willbe closed to exhaust, and the pump P2 will be operative through thevalve V to raise the lifter head Sil.

The pump P2 is of such capacity that the lifter head moves upward morerapidly than the ram Il, thus returning the broach B to the position Ain Fig. 7 by the time the puller head has reached its raised position.When the lifter head 99 is fully raised, the cam |34 opens the controlvalve |30, thus venting the pipe |4 and connecting the pump P2 toexhaust. At the same time, the knock-off arm 30 engages the upper collar2l on the rod 26 and returns the main pump P to no-discharge position,thus completing the bro-aching cycle.

Having described the operation of a machine embodying my invention, itwill be clear that the machine is fully safeguarded and that theoperator cannot cause damage by improper sequence of operation.

As previously explained in detail, the lifter head cannot be starteddownward to insert the broach in the work unless the ram is in fullyraised position to receive the broach. The ram cannot be starteddownward for a broaching stroke unless the key has been inserted in thelower end of the broach. The pump P is returned to no-discharge positionautomatically at the lower end of the stroke, and the key il!) issimultaneously withdrawn automatically. The lever 85 cannot be shiftedto close the switch 5S without withdrawal of the key 10, and closing ofthe switch 58 will not cause the pump P to be rendered operative to liftthe ram unless the nished work has been removed from the path of thelight ray which controls the photoelectrc relay 51.

The control valves |30 and 3| vent the pipe Hl and connect the pump P2to exhaust as soon as the puller head 9i) reaches either end of its pathof travel, and the switch |22 is closed to reverse the valve V only onupward movement of the lifter head by pressure of the ram on the broachB after insertion of the upper end of the broach in the holder 25.

The machine is operated by simply closing the switches 60 and 58 inpredetermined order, and the operator has nothing else to do except toinsert and remove the work.

The photoelectric control of work removal is not limited in utility tobreaching machines but is capable of more general application.

Having thus described my invention and the advantages thereof, I do notwish to be limited to the details herein disclosed, otherwise than asset forth in the claims, but what I claim is:

1. In a vertical hydraulic pull-down broaching machine comprising apuller head, a lifter head, a reversible-discharge pump for said pullerhead and hydraulic shifting mechanism for said pump, that improvementwhich consists in providing auxiliary hydraulic operating means for saidlifter head, and control devices for said auxiliary means which ventsaid auxiliary means after said lifter head has completed its downstroke and thereby permit said lifter head to be moved upward a limiteddistance by said puller head without substantial hydraulic resistance tosuch movement.

2. In a vertical hydraulic pull-down broaching machine comprising apuller head, a lifter head, a reversible-discharge pump for said pullerhead and hydraulic shifting mechanism for said pump, that improvementwhich consists in providing auxiliary hydraulic operating means for saidlifter head, and control devices for said auxiliary means which ventsaid auxiliary means after said lifter head has completed its downstroke and thereby permit said lifter head to be moved upward a limiteddistance by said puller head without substantial hydraulic resistance tosuch movement, and which thereafter render said auxiliary meansoperative to complete the upward movement of the lifter head.

3. In a vertical hydraulic pull-down broaching machine comprising apuller head, a lifter head, a reversible-discharge pump for said pullerhead and hydraulic shifting mechanism for said pump, that improvementwhich consists in providing auxiliary hydraulic operating means for saidlifter head, and control devices for said auxiliary means which ventsaid auxiliary means after said lifter head has completed its downstroke and thereby permit said lifter head to be moved upward a limiteddistance by said puller head without substantial hydraulic resistance tosuch movement, and which thereafter render -said auxiliary meansoperative to complete the upward movement of the lifter head atincreased speed, thereby separating said broach from said puller head.

4. In a vertical hydraulic pull-down broaching machine comprising apuller head, a lifter head and a reversible-discharge main pump for saidpuller head, that improvement which consists in providing a continuouslyoperating auxiliary pump for said lifter head, vent valves engageable bysaid lifter head as it approaches its upper and lower limits of travel,and a relief valve controlled thereby and effective to bly-pass theoutput of said auxiliary pump at reduced pressure when said lifter headcompletes its travel in either direction and one of said vent valves isopened.

5. In a vertical hydraulic pull-down broaching machine comprising apuller head, a reversble-discharge pump for said puller head andhydraulic sluiting mechanism for said pump, that improvement whichconsists in providing a pair of electric switches controlling saidshifting mechanism, a broach key inserting device for said puller head,and a manual member operable when shifted in one direction to move saiddevice to insert said key and to simultaneously close one of saidcontrol switches to cause said shifting mechanism to be operated.

6. In a vertical hydraulic pull-down broaching machine comprising apuller head, a reversible-discharge pump for saidpuller head andhydraulic shifting mechanism for said pump, that improvement whichconsists in providing a pair of electric switches controlling saidshifting mechanism, a broach key inserting device for said puller head,a manual member operable when shifted in one direction to move saiddevice to insert said key and to simultaneously close one of saidcontrol switches to cause said shifting mechanism to be operated, andmeans to automatically withdraw said key at the completion of thebroaching stroke, said manual member being thereafter operable whenshifted in the opposite direction to close the second control switch.

7. In a vertical hydraulic pull-down broaching machine comprising apuller head, a reversible-discharge pump for said puller head andhydraulic shifting mechanism for said pump, that improvement whichconsists in providing a pair of electric switches controlling saidshifting mechanism, a broach key inserting device for said puller head,and a manual member operable when shifted in one direction to move saiddevice to insert said key and to simultaneously close one of saidcontrol switches to cause said shifting mechanism to be operated, andoperable when shifted in the opposite direction to close the secondswitch and to simultaneously withdraw said key if the key is still inbroach holding position.

8. In a vertical hydraulic pull-down broaching machine comprising apulled head, a reversible-discharge pump for said puller head andhydraulic shifting mechanism for said pump, that improvement whichconsists in providing a pair of electric switches controlling saidshifting mechanism, a broach key inserting device for said puller head,a manual member operable when shifted in one direction to move saiddevice to insert said key and to simultaneouslyvclose one of saidcontrol switches to cause said shifting mechanism to ble operated, andoperable when shifted in the opposite direction to close the secondswitch, said member being held yieldingly in mid position and having alost-motion connection with said device which permits said device toautomatically withdraw said key without moving said manual member toclose said second switch.

9. In a vertical hydraulic pull-down broaching machine comprising apuller head, a lifter head, a reversible-discharge pump for said pullerhead and hydraulic shifting mechanism for said pump, that improvementwhich consists in providing a continuously operating auxiliary pump forsaid lifter head, a pilot-operated relief valve for said pump, upper andlower normally closed control valves for said relief valve, and means onsaid lifter head to open one of said control valves at its upper limitof travel and the other control valve at its lower limit of travel,thereby causing said relief valve to by-pass the discharge of said pumpto atmospheric storage at both ends of the lifter head travel.

10. In a vertical hydraulic pull-down breaching machine comprising apuller head, a lifter head, a reversible-discharge pump for said pullerhead and hydraulic shifting mechanism for said pump, that improvementwhich consists in providing a continuously operating auxiliary pump forsaid lifter head, a pilot-operated relief valve for said pump, upper andlower normally closed control valves for said relief valve, and means onsaid lifter head to open one of said control valves at its upper limitof travel and the other control valve at its lower limit of travel, saidrelief valve connecting said auxiliary pump to operate said lifter headwhen both control valves are closed but connecting said pump toatmospheric storage when either control valve is open.

11. In a vertical hydraulic pull-down broaching machine comprising apuller head, a reversible-discharge pump for said puller head andhydraulic shifting mechanism for said pump, that improvement whichconsists in providing a broach key inserting device for said pullerhead, electric means coordinated with said inserting device andeifective to render said hydraulic shifting mechanism operative toadjust said pump to discharge in a selected direction after said key hadbeen inserted, and direct and positively acting mechanical meanseffective to restore said pump to no-discharge position when the desiredtravel of the puller head is completed in said selected direction.

12. In a vertical hydraulic pull-down broaching machine comprising apuller head, a reversible-discharge pump for said puller head andhydraulic shifting mechanism for said pump, that improvement whichconsists in providing electric means to render said hydraulic shiftingmechanism operative to adjust said pump to discharge in a selecteddirection, direct and positively acting mechanical means effective toautomatically restore said pump to no-discharge position when thedesired travel of the puller head is completed in either direction, andmeans to automatically condition said hydraulic shifting means forautomatic mechanical control as soon as the operative circuit of saidelectric means is broken.

13. In a vertical hydraulic pull-down broaching machine, a lifter head,hydraulic actuating means therefor, a valve for said means, a separatesolenoid to actuate said valve in each direction, circuits for saidsolenoids, a manually operated switch in one circuit, a second switch inthe other circuit, and means on said lifter head effective to close saidsecond switch as said lifter head moves upward only.

14. In a broaching machine, a broaching ram, a piston connected by apiston rod to said ram, a cylinder for said pump, of said connectionsfrom said pump to both ends cylinder, a control pipe connected to thepiston rod end of said cylinder, and a normally closed vent valveconnected to the other end of said cylinder, said vent valve beingopened by pressure in said control pipe and permitting surplus displacedoil to escape.

15. In a vertical hydraulic pull-down broaching machine comprising a xedwork support, a reciprocable puller head, a reciprocable lifter head, areversible-discharge pump for actuating said puller head and hydraulicshifting mechanism for said pump, that improvement which consists inproviding auxiliary hydraulic operating means for said lifter head, andcontrol devices for said auxiliary means which prevent downward movementof said lifter head to insert a broach in the puller head unless saidpuller head is in fully raised position.

16. In a vertical hydraulic pull-down broaching machine comprising afixed work support, a reciprocable puller head, a reversible-dischargepump for actuating said puller head and hydraulic shifting mechanism forsaid pump, that improvement which consists in providing a control valvefor said hydraulic shifting mechanism, and a device effective toprevent'movement of said control valve to cause said 'hydraulicmechanism to be actuated to shift said pump for a return stroke so longas a piece of work remains in breaching position on the fixed worksupport.

17. In a vertical hydraulic pull-down broaching machine comprising afixed work support, a reciprocable puller head, a reversible-dischargepump for actuating said puller head and hydraulic shifting mechanism forsaid pump, that improvement which consists in providing a control valvefor said hydraulic shifting mechanism, and a photoelectric relayeiective to prevent movement of said control valve to cause saidhydraulic mechanism to be actuated to shift said pump for a returnstroke so long as a piece of work remains in broaching position on thefixed work support.

KENNETH C. MONROE.

piston, a reversible-discharge

